We propose to use a well-established clinical information system to identify "indicators" of errors in ambulatory patient care in 18 practices which are part of a practice based research network (ResNet). A clinical focus team, including a specialty physician, general internist and nurse, will analyze these indicator data using root cause and multidimensional exploratory data analysis methods to identify changes in the delivery system that can potentially reduce the "indicators". Because of the demonstrated effectiveness of clinical decision support systems (CDSS) in changing physician behavior, we propose to prospectively test this specific change in the delivery system. We will also test the value of delivering summarized indicator data to the physicians along with "academic detailing" and the synergies between this change with CDSS. The primary outcome will be the number of "indicators" identified from the clinical information system.